How much?
I usually get it as close to zero as I can, but I re-strung with a set of medium flats last night, and the relief was a litlle more than I'm used to. The bass sounds good, has no buzzes, and plays pretty good...I'm inclined to leave it, just because the sound seems to have opened up and really sing. Sometimes when a rod is really tight, it seems to me to choke off the tone.
So, how much relief do you keep in a neck?